package com.youngjun.common.util;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

/**
 * 验证码图片生成工具
 * 使用JAVA生成的图片验证码，调用getRandcode方法获取图片验证码，以流的方式传输到前端页面。
 * @author YoungJun
 * @date 2021/06/23
 */
public class CaptchaUtils {

    private static Random random = new Random();
    private static String randString = "23456789ABCDEFGHJKMNPQRSTUVWXYZabcdefghjkmnpqrstuvwxyz";// 随机产生的字符串

    private static int width = 80;// 图片宽
    private static int height = 26;// 图片高
    private static int lineSize = 40;// 干扰线数量
    private static int stringNum = 4;// 随机产生字符数量

    /*
     * 获得字体
     */
    private static Font getFont() {
        return new Font("Fixedsys", Font.BOLD, 18);
    }

    /*
     * 获得颜色
     */
    private static Color getRandColor(int fc, int bc) {
        if (fc > 255)
            fc = 255;
        if (bc > 255)
            bc = 255;
        int r = fc + random.nextInt(bc - fc - 16);
        int g = fc + random.nextInt(bc - fc - 14);
        int b = fc + random.nextInt(bc - fc - 18);
        return new Color(r, g, b);
    }

    /*
     * 绘制字符串
     */
    private static String drowString(Graphics g, String randomString, int i) {
        g.setFont(getFont());
        g.setColor(new Color(random.nextInt(101), random.nextInt(111), random.nextInt(121)));
        String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));
        randomString += rand;
        g.translate(random.nextInt(3), random.nextInt(3));
        g.drawString(rand, 13 * i, 16);
        return randomString;
    }

    /*
     * 根据字符绘制字符串
     */
    private static String drowString(Graphics g, String randomString) {
        for (int i = 1; i <= stringNum; i++) {
            g.setFont(getFont());
            g.setColor(new Color(random.nextInt(101), random.nextInt(111), random.nextInt(121)));
            String rand = randomString.substring(i -1, i);
            g.translate(random.nextInt(3), random.nextInt(3));
            g.drawString(rand, 13 * i, 16);
        }
        return randomString;
    }

    /*
     * 绘制干扰线
     */
    private static void drowLine(Graphics g) {
        int x = random.nextInt(width);
        int y = random.nextInt(height);
        int xl = random.nextInt(13);
        int yl = random.nextInt(15);
        g.drawLine(x, y, x + xl, y + yl);
    }

    /*
     * 获取随机的字符
     */
    private static String getRandomString(int num) {
        return String.valueOf(randString.charAt(num));
    }


    /**
     * 生成随机字符图片
     */
    public static String getCode(OutputStream outputStream) throws IOException {
        // BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
        Graphics g = image.getGraphics();// 产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
        g.fillRect(0, 0, width, height);
        g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
        g.setColor(getRandColor(50, 200));
        // 绘制干扰线
        for (int i = 0; i <= lineSize; i++) {
            drowLine(g);
        }
        // 绘制随机字符
        String randomString = "";
        for (int i = 1; i <= stringNum; i++) {
            randomString = drowString(g, randomString, i);
        }
        g.dispose();
        ImageIO.write(image, "JPEG", outputStream);// 将内存中的图片通过流动形式输出到客户端
        return randomString;
    }

    /**
     * 根据字符生成图片
     */
    public static String getCode(OutputStream outputStream, String code) throws IOException {
        // BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
        Graphics g = image.getGraphics();// 产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
        g.fillRect(0, 0, width, height);
        g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
        g.setColor(getRandColor(50, 200));
        // 绘制干扰线
        for (int i = 0; i <= lineSize; i++) {
            drowLine(g);
        }
        // 绘制随机字符
        drowString(g, code);
        g.dispose();
        ImageIO.write(image, "JPEG", outputStream);// 将内存中的图片通过流动形式输出到客户端
        return code;
    }

    // 随机生成字符串
    public static String getRandCode() {
        String randomString = "";
        for(int i = 0; i < stringNum; i++){
            String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));
            randomString += rand;
        }
        return randomString;
    }
}